Prepare the spaghetti in salted, boiling water according to package directions. Drain and rinse in cold water. Once drained, pour the spaghetti into a large container with a lid. Pour half the dressing over the spaghetti, toss to coat, cover and refrigerate until needed. This can be done 24 hours in advance.
Add the chopped vegetables to the spaghetti and pour over all remaining Italian dressing. Sprinkle the seasoned salt, Parmesan and black pepper over the spaghetti. Toss to combine. Check seasoning and add more seasoned salt, if needed. The amount of salt needed depends on the kind of dressing you used. Garnish with additional Parmesan and serve immediately or refrigerate until needed.
Salad with stay fresh for several days if refrigerated in a sealed container. Toss to freshen before serving. Leftovers are terrific!